192 THE ANATOMY OP THE HORSE. 



enters the cranium by the foramen laceram basis cranii. Its mode of 

 entrance and its distribution to the brain will be examined at a later 

 stage. 



The External Carotid Artery (Plates 31 and 32). This vessel may, 

 for the purposes of description, be divided into two portions. The first 

 portion, comprising two-thirds of the artery, is included between the gut- 

 tural pouch inwardly, and the stylo-maxillaris, digastric, and stylo-hyoid 

 muscles outwardly. It emerges from beneath the last-named muscle, 

 and joins the second portion by passing betjyeen the muscle and the 

 posterior edge of the great cornu of the hyoid bone. It is crossed 

 inwardly by the 9th, and outwardly by the 1 2th nerve. The second 

 portion passes obliquely upwards and forwards on the great cornu, at 

 the upper part of which, and under cover of the parotid gland, it divides 

 into the superficial temporal and internal maxillary arteries. The 

 collateral branches of the vessel are : the submaxillary, maxillo-muscular, 

 and posterior auricular arteries. The last two spring from the second 

 portion of the artery, and have already been dissected. 



The Submaxillary or Facial Artery is detached from the 

 external carotid beneath the digastric muscle. It is a vessel of large 

 calibre, being nearly equal to the parent vessel beyond its point of 

 detachment. It descends over the pharynx, being nearly parallel to the 

 posterior edge of the great cornu, and about an inch behind it. At first 

 under cover of the digastric and stylo-hyoid muscles, it then turns 

 round the anterior edge and outer surface of the stylo-hyoid where the 

 intermediate tendon of the digastric plays through it. Continuing its 

 course, it crosses Wharton's duct and the lower extremity of the sub- 

 maxillary gland to the outer side, and appears in the intermaxillary 

 space between the internal pterygoid and subscapulo-hyoid muscles. 

 Its further course in the intermaxillary space and on the face has already 

 been followed. Behind the great cornu the artery is in company with 

 the 12th nerve. From its origin to the extremity of the submaxillary 

 gland, it detaches three collateral branches, viz., the pharyngeal, lingual, 

 and submental arteries. 



1. The Pharyngeal Artery is a small branch given off at the anterior 

 edge of the stylo-hyoid or under cover of that muscle. It reaches the 

 pharynx by passing beneath the great cornu, crossing either outwardly 

 or inwardly the 9th nerve. It is distributed to the pharynx, giving also 

 a forward branch to the soft palate. 



2. The Lingual Artery, whose volume is about equal to that of the 

 distal part of the parent trunk, has its point of origin over the tip of 

 the thyroid cornu. It descends on the cerato-hyoid muscle, and reaches 

 the tongue by passing beneath the great hyo-glossus muscle. It is the 

 main vessel of supply to the tongue, and will be followed in the dissec- 

 tion of that organ. 



